High acidity in female vagina is one important anti-infective mechanism of the vagina and is of great significance for vaginal health. Lactobacilli and other Gram-positive bacilli that can produce and resist acids serve an important role in maintaining the normal acidity in the vagina by keeping the vaginal pH value in the range from 4.0 to 4.6. They are the physiological bacterial flora of vagina, whereas Gram-negative bacilli, Gram-negative cocci, and Gram-positive cocci are relatively less abundant in the healthy vagina.
When the Gram-positive bacilli are reduced or disappear in vagina, vaginal pH value rises and disturbance of vaginal bacterial flora results from abnormal increases of Gram-negative bacilli, Gram-positive cocci and Gram-negative cocci, which can cause harm to the human body and lead to a range of diseases. The most typical condition resulting from altered vaginal flora is bacterial vaginosis (BV). BV is characterized by the reduction or even disappearance of Lactobacillus and other Gram-positive bacilli in the vagina, accompanied by decreased acidity (pH value>4.6) in the vagina, and abnormal increases of such bacteria as Gram-negative bacilli including Gardnerella, Bacteroides and motile-curved bacilli; Gram-negative cocci such as Veillonella; and Gram-positive cocci such as Streptococcus. Such changes in the bacterial flora can cause vaginal secretions to exhibit an unpleasant odor, and may be associated with pruritus of vulva, and symptoms. In addition, BV may also be related to IUGR [1], PTL, PROM [2], abortion, and obstetric infections such as chorio-amnionitis, puerperal endometritis, vaginal wall phlegmon after hysterectomy, female upper genital tract infection (salpingitis), and urinary infection, etc. [3]. A high rate of morbidity is associated with vaginal bacterial flora disturbance. According to one report, about 45% or more vaginitis cases result from disturbance of vaginal bacterial flora [3], and 4-15% of American female students in universities suffer from bacterial vaginosis [4], which has led to serious compromise to health and quality of life.
There are few options for treatment of reduced Gram-positive bacilli colonization, decreased vaginal acidity, and related disturbances of vaginal bacterial flora, vaginitis, and bacterial vaginosis. Therapeutic options currently include:
1) Antibacterial drugs which are used to suppress the growth of Gram-negative bacilli and other abnormal bacteria. These most commonly include clindamycin and metronidazole [5-6]. These drugs suppress the bacteria that are abnormally increased in the vagina but may also affect the Gram-positive bacilli. After administration of these drugs, the Gram-positive bacilli (lactobacilli) can not be restored very well, and it is very difficult to lower the pH value in the vagina to normal level.
2) Lactic acid-containing pharmaceutical compositions. Vaginal secretions from patients suffering from bacterial vaginosis have elevated pH values. Swedish researchers used lactic acid gel for the improvement and recovery of the low-acidity conditions in vagina, and reported that this treatment can restore the Gram-positive bacilli (lactobacilli) in the vaginas of some of the patients [7]. But the study also showed that the lactic acid pharmaceutical preparation is less effective than the antibacterial drugs [8].
3) Lactobacillus preparations. Most of the Gram-positive bacilli in vagina are lactobacillus. If there is disturbance of vaginal bacterial flora, the lactobacilli will be reduced or disappear, and Gram-negative bacilli, Gram-negative, and Gram-positive cocci, will increase. The Gram-positive bacilli in the vagina of some patients can be restored by directly adding lactobacilli in the vagina [9]. However, stable colonization is generally not achieved. Moreover, it is difficult to maintain viability of the lactobacillus preparations during storage, with viable counts in such preparations decreasing during storage, compromising their useful shelf life [10].
The international Patent Application WO94/02148 discloses a pharmaceutical composition for treating vulvitis and vulvovaginitis, and indicates that such compositions can promote restoration of vaginal epithelium tissues while alleviating the symptoms. Its preferred composition comprises 7 to 8 active substances. Some preferred compositions may contain 3.0-15.0% (by weight/volume) lactose or glucose. As mentioned in page 5 lines 8-10 of the published specification, the lactose or glucose contained in these compositions is used as carbon source. But this application does not mention that saccharides can be used solely as the effective component for treating vulvitis and vulvovaginitis, and nor does it disclose explicitly or implicitly that the disclosed compositions can stimulate the growth of Gram-positive bacilli in vagina. Furthermore, it does not indicate that any other kinds of sugar can be used as active components of a composition for treating related vaginal diseases. Besides, as mentioned in page 5 lines 17-18 of the specification, this application emphasizes that it is important for the pH value of the compositions be between 2 and 3.5.
The U.S. Pat. No. 3,860,707 teaches a method for treating trichomonal vaginitis and monilial vaginitis. This method comprises administering lactulose into the vagina. This patent also indicates that lactulose can be administered after being mixed with some carriers such as glucose, lactose and galactose, wherein lactulose is required to have a concentration as high as 50%, and the mixture also contains 5% lactose, 8% galactose as carriers, as mentioned in column 1 lines 51-55 and column 5 lines 1-5 of the patent specification. The quantity of lactulose is 4-10 grams administered with each dose, which is taken once or twice daily, as shown in Column 4 Lines 63-66 of the specification. But this patent does not describe the treatment effectiveness on bacterial vaginosis or other vaginal diseases different from monilial vaginitis, nor does it suggest that the lactulose of low or medium concentration (2.5-17%) and small dosage (daily total amount 0.24-2.1 grams) would be able to stimulate the growth of Gram-positive bacillus and increase the acidity of the vagina. Furthermore, it fails to indicate whether any saccharide other than lactulose has treatment effects.
European Patent Application EP-A-0257007 discloses a pharmaceutical composition containing lactic acid and buffering substances and substrate to support growth of lactobacillus, which can be used to improve micro-environment in vagina and suppress the growth of harmful bacteria in the vagina, so as to facilitate the growth of lactobacilli. This patent application discloses that glycogen or lactose can be used as the said substrate. But as mentioned in Column 6 Line 10-14 of the specification, the main ingredient of this composition is lactic acid. The lactic acid and the glycogen and/or lactose are incorporated in a ratio by weight of from 20:1 down to 500:1, and the content of glycogen and/or lactose is only 0.1-0.166% (W/V). It also stresses that the pH value of the pharmaceutical composition should be adjusted to 3.5 to 4.0, which is very important. The in vitro experimental results disclosed in this application show that this composition can effectively and selectively kill pathogenic bacteria, and lactobacilli can survive in this composition for a longer time than the pathogenic microorganisms. But no test in vitro or vivo shows that this composition can stimulate the growth of lactobacilli or produce acids. Nor does this application mention the treatment effect of glycogen or lactose or any other saccharides when they are used separately as active ingredients.
GB21 12285A discloses a lotion composition for cleaning the vagina. It is a buffering liquid comprising acetic acid or lactic acid plus sodium acetate with a pH value of 5.71 to 6.2 as shown in the examples. It also contains nutrients to support the growth of lactobacillus [1-2% (W/V) glucose and unsaturated fatty acid]. It also generally mentions inclusion of mono- and/or disaccharides. The main therapeutic mechanism of this composition is that the buffering lotion comprising acetic acid or lactic acid plus sodium acetate can selectively suppress pathogens and not suppress lactobacilli. As shown in claims 2 and 3 and the in vitro test data of this application, this lotion can effectively suppress many kinds of pathogens, and lactobacilli survive in this composition for a longer time. No data from test in vitro or vivo indicates that this lotion has an activity of promoting the growth of lactobacilli and producing acid, nor does it indicate the treatment effect of glucose or any other sugar when used separately as active ingredients. This application teaches that lactobacilli regulate pH value in vagina to about 5.8, as shown in Page 1 Lines 20-23 of the specification, which is strongly contradicted by most knowledgeable investigators.
The above-mentioned pharmaceutical compositions disclosed in patent applications EP-A-0257007 and GB2112285A which contain lactic acid, acetic acid and other selective inhibitors as main active ingredients have strong suppressive action on pathogens but no explicit suppressive action on lactobacilli, although they may indirectly facilitate the growth of vaginal lactobacilli. These compositions themselves, however, cannot directly promote significant growth of lactobacilli, and only regulate vaginal acidity for a short time. Therefore, it remains very difficult to restore the physiological conditions dominated by the Gram-positive bacillus-flora and to restore the vaginal acidity to its normal value.
The object of the present invention is to provide a composition for promoting the growth of Gram-positive bacilli and the production of acids, and thus increase the acidity in the vagina. Another object of the present invention is to provide a method by using such composition for reversing the reduction of Gram-positive bacilli, lack of vaginal acidity and treating related vaginal diseases.
In order to seek a composition which is effective in promoting the growth of Gram-positive bacilli, producing acid, and enhancing the acidity in the vagina, the inventor has conducted an extensive study, performed tests by using various pharmaceutical compositions known in the prior art, and has not found any compositions promoting the growth of Gram-positive bacilli among the existing compositions. After repeated tests and intensive study, the inventor has found very surprisingly that sucrose and maltose both have a strong effect in promoting the growth of Gram-positive bacilli and producing acids if they are presented in a concentration and at a pH value in specific ranges. Combined in vitro culturing experiments show that the two saccharides can stimulate the growth of Gram-positive bacilli, increasing their numbers significantly. To our surprise, although pH values above 4.6 in vagina are considered un-physiologic, and most of state-of-the-art technologies stress that the pharmaceutical compositions used in vagina must have a pH value equal to 4.0 or below, the inventor has discovered that, if they have pH value between 4.1 and 7.2, and especially above pH 5.0, sucrose and maltose can stimulate the growth of Gram-positive bacilli of women vagina and the production of acid, and are able to decrease the pH value in vagina to less than 4.6. However, if they have pH values of 4.0 or less, they do not exert significant growth-promoting effects on Gram-positive bacilli nor upon acid production and the pH of the vagina can rarely be reduced to below 4.6. Based on the above discoveries and further study, the inventor has completed the present invention.